There is known a method of electrolytic anodic polishing of steel articles by direct current in a chromium-phosphorus-sulfuric acid electrolyte (A.M. Yampolski "Travleniye metallov", 1980, Metallurgiya/Moscow/, p. 51) performed by submerging articles in the electrolyte containing, % by weight:
______________________________________ orthophosphoric acid 65-85 chromic anhydride 6-12 sulfuric acid 5-15 ______________________________________
the voltage being 10 to 25 V, and the temperature being 30.degree.-70.degree. C. The electrolytic polishing is conducted with the anodic current density of 50-60 A/dm.sup.2 for 3-15 mn.
There is also known a method of electrolytic polishing of articles made of copper and its alloys by way of electrolysis in an aqueous solution of phosphoric acid (the density of the solution being .rho.=1.6 g/cm.sup.3) (A.M. Yampolski "Travleniye metallov", 1980, Metallurgiya (Moscow/, p. 99), or else in an electrolyte containing 385 g of potassium pyrophosphate and 853 g of water, at 20.degree.-50.degree. C. for 1.5-3 mn (SU, A, 177732).
There is still further known a method of electrolytic polishing of articles made of aluminium and its alloys, in an electrolyte containing 20-25% by weight of sulfuric acid, at 18.degree.-20.degree. C. and under a voltage of 6-12 V (Witt C., "Galvanotechnik", 1981, V.72, No. 10, pp.1073-1075).
The abovementioned methods are based on the use of high-concentration solutions of expensive and toxic substances; they are characterized by relatively long duration of the polishing operation and require prolonged pretreatment of the surface of an article prior to the electrolytic polishing operation, including degreasing, etching (pickling), flushing, etc., which adversely affects the overall productivity and efficiency, to say nothing of the considerable input of power and labour.
There is also known a method of electrochemical machining of articles made of electrically conducting materials, including treating the articles at 220-380 V in an electrolyte containing 20% aqueous solution of ammonium chloride at 35.degree. C. (V. N. Duradzhi et al. "Elektronnaya obrabotka materialov"/Electronic Machining of Materials/, 1978, No. 5, pp.13-17).
However, this last-mentioned process fails to produce a surface finish of the articles finer than R.sub.a =0.28 . . . 0.32 .mu.m, with the reflection factor of the machined surface within 30-40%. Furthermore, the process requires the use of an electrolyte of a relatively high concentration (20%), which increases the machining cost.